In general, a drilling machine, which is used to drill deep holes into the ground for purposes of drilling, soil testing or development of underground water, may be classified into a type in which a drilling work is performed while rotating a rod having a bit, and a type in which a drilling work is performed by rotating a rod having a bit or a cutter and striking the bit or the cutter using the rod.
A conventional drilling machine is disclosed in Korean Patent No. 624233. The disclosed drilling machine comprises a main body having a driving device such as an engine, a leader supported by the main body, and a head sliding along the leader and generating an elevational force or a rotational force by a driving device provided in the main body, a rod coupled to the head and elevating or rotating by the head, and a drilling unit provided at a front end of the rod and perforate the ground while elevating or rotating along with the rod.
Since a drilling work using the aforementioned drilling machine is performed in a state in which a lead is maintained at a predetermined angle with respect to a main body, a position of the lead with respect to the main body is fixed in consideration of safety. The position of the lead is fixed by installing separate brackets on the main body of the drilling machine and the lead to then fix the lead using a coupling device of the main body of the drilling machine and the lead or by installing separate support bars between the lead and the main body.
However, the aforementioned lead position fixing structure using the coupling device or the support bars has several problems in that a worker cannot eliminate the structure in the middle of working, and it may be damaged when a cylinder as an actuator for adjusting a rotation angle of the lead is actuated. In particular, when the cylinder is actuated to adjust the rotation angle in a state in which the position of the lead is fixed, peripheral devices for rotating the lead with respect to the main body may be damaged.